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    PR # 31046                                                                   
     Many black-hole binaries (including candidates) are transients. Stati       
     stics show that more than several hundred of black-hole binaries exis       
     t in the Galaxy, which are X-ray quiescent most of the time. There ar       
     e some evidence that they are emitting X-rays at very low level durin       
     g quiescence. Only ASCA observations allow systematic study of black-       
     hole binaries in X-ray quiescence. Their spectral characteristics in        
     comparison with transient neutron-star binaries in quiescence is impo       
     rtant for understanding the mechanism of transient outburst.                
                                                                                 
                                                                                 
                                                                                 
                                                                                 
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